.TH std::isxdigit 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::isxdigit \- std::isxdigit

.SH Synopsis
   Defined in header <cctype>
   int isxdigit( int ch );

   Checks if the given character is a hexadecimal numeric character
   (0123456789abcdefABCDEF).

   The behavior is undefined if the value of ch is not representable as unsigned char
   and is not equal to EOF.

.SH Parameters

   ch - character to classify

.SH Return value

   Non-zero value if the character is a hexadecimal numeric character, zero otherwise.

.SH Notes

   std::isdigit and std::isxdigit are the only standard narrow character classification
   functions that are not affected by the currently installed C locale. although some
   implementations (e.g. Microsoft in 1252 codepage) may classify additional
   single-byte characters as digits.

   Like all other functions from <cctype>, the behavior of std::isxdigit is undefined
   if the argument's value is neither representable as unsigned char nor equal to EOF.
   To use these functions safely with plain chars (or signed chars), the argument
   should first be converted to unsigned char:

 bool my_isxdigit(char ch)
 {
     return std::isxdigit(static_cast<unsigned char>(ch));
 }

   Similarly, they should not be directly used with standard algorithms when the
   iterator's value type is char or signed char. Instead, convert the value to unsigned
   char first:

 int count_xdigits(const std::string& s)
 {
     return std::count_if(s.begin(), s.end(),
                       // static_cast<int(*)(int)>(std::isxdigit)         // wrong
                       // [](int c){ return std::isxdigit(c); }           // wrong
                       // [](char c){ return std::isxdigit(c); }          // wrong
                          [](unsigned char c){ return std::isxdigit(c); } // correct
                         );
 }

.SH Example


// Run this code

 #include <cctype>
 #include <climits>
 #include <iostream>

 int main()
 {
     for (int c = 0; UCHAR_MAX >= c; ++c)
         if (isxdigit(c))
             std::cout << static_cast<char>(c);
     std::cout << '\\n';
 }

.SH Output:

 0123456789ABCDEFabcdef

.SH See also

                         checks if a character is classified as a hexadecimal digit by
   isxdigit(std::locale) a locale
                         \fI(function template)\fP
   iswxdigit             checks if a wide character is a hexadecimal character
                         \fI(function)\fP
   C documentation for
   isxdigit

        ASCII values            characters    iscntrl  isprint  isspace  isblank  isgraph  ispunct  isalnum  isalpha  isupper  islower  isdigit  isxdigit
decimal hexadecimal   octal                   iswcntrl iswprint iswspace iswblank iswgraph iswpunct iswalnum iswalpha iswupper iswlower iswdigit iswxdigit
0–8     \\x0–\\x8     \\0–\\10    control codes   ≠0       0        0        0        0        0        0        0        0        0        0        0
                              (NUL, etc.)
9       \\x9         \\11       tab (\\t)        ≠0       0        ≠0       ≠0       0        0        0        0        0        0        0        0
                              whitespaces
10–13   \\xA–\\xD     \\12–\\15   (\\n, \\v, \\f,    ≠0       0        ≠0       0        0        0        0        0        0        0        0        0
                              \\r)
14–31   \\xE–\\x1F    \\16–\\37   control codes   ≠0       0        0        0        0        0        0        0        0        0        0        0
32      \\x20        \\40       space           0        ≠0       ≠0       ≠0       0        0        0        0        0        0        0        0
33–47   \\x21–\\x2F   \\41–\\57   !"#$%&'()*+,-./ 0        ≠0       0        0        ≠0       ≠0       0        0        0        0        0        0
48–57   \\x30–\\x39   \\60–\\71   0123456789      0        ≠0       0        0        ≠0       0        ≠0       0        0        0        ≠0       ≠0
58–64   \\x3A–\\x40   \\72–\\100  :;<=>?@         0        ≠0       0        0        ≠0       ≠0       0        0        0        0        0        0
65–70   \\x41–\\x46   \\101–\\106 ABCDEF          0        ≠0       0        0        ≠0       0        ≠0       ≠0       ≠0       0        0        ≠0
71–90   \\x47–\\x5A   \\107–\\132 GHIJKLMNOP      0        ≠0       0        0        ≠0       0        ≠0       ≠0       ≠0       0        0        0
                              QRSTUVWXYZ
91–96   \\x5B–\\x60   \\133–\\140 [\\]^_`          0        ≠0       0        0        ≠0       ≠0       0        0        0        0        0        0
97–102  \\x61–\\x66   \\141–\\146 abcdef          0        ≠0       0        0        ≠0       0        ≠0       ≠0       0        ≠0       0        ≠0
103–122 \\x67–\\x7A   \\147–\\172 ghijklmnop      0        ≠0       0        0        ≠0       0        ≠0       ≠0       0        ≠0       0        0
                              qrstuvwxyz
123–126 \\x7B–\\x7E   \\172–\\176 {|}~            0        ≠0       0        0        ≠0       ≠0       0        0        0        0        0        0
127     \\x7F        \\177      backspace       ≠0       0        0        0        0        0        0        0        0        0        0        0
                              character (DEL)
